Method of making a ball point pen or a refill therefor

ABSTRACT

This invention relates to a method of manufacturing ball point pens. In the method the ball is force-fitted into the ball housing with a force sufficient to cause a narrowing of the feed ducts for supplying writing medium from the reservoir to the ball such that at least a part of each duct has a maximum crosssectional area of 2,000 Mu 2, preferably, 1,000 Mu 2.

O United States Patent 1 3,678,565 Lmz et al. [451 July 25, 1972 [54] METHOD OF MAKING A BALL POINT [56] References Cited PEN OR A REFILL THEREF R [72] I N 0 UNITED STATES PATENTS nventors: Georg Linz, uremberg; Lothar Summer xatzwang, both Germany 3,470,603 10/1969 Azzantl ..29/44l BP [7 3] Assignee: Firms Georg Linz, Nuremberg, Germany Primary Examiner'lhomas H. Eager Filed: Feb- 1971 fizggly-gzoggel F. Dvorak, Stephen T. Skrydlak and 211 App]. No.: 112,943

[57] ABSTRACT [30] Foreign Application Priority Data This invention relates to a method of manufacturing ball point Jul 0 9 G pens. In the method the ball is force-fitted into the ball housy up 20 34 2749 ing with a force sufiicient to cause a narrowing of the feed ducts for supplying writing medium from the reservoir to the 8|. n such that at least a part f ach duct has a maximum p 1,0 [58] Field 0! Search ..29/44l B, 441 P, 149.5 B, 441 cross secuonal area of 2,000 n preferably 00 I 3 Claims, 3 Drawing Figures PATENIEB JUL25 m2 SHEET 1. 0F 2 FIG.1

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METHOD OF MAKING A BALL POINT PEN OR A REFILL THEREFOR This invention relates to a method of pen or a refill therefor.

British Pat. No. 1,107,944 describes a ball point pen having a reservoir for a pasty writing medium and a ball housing connected to one end of the reservoir and providing a support wall and a bearing seating for the ball, the reservoir having at or near its other end an end aperture and having an internal cross-section of such dimensions that when the ball point pen is held with its writing point upwards, the writing medium does not flow through the end aperture, there being formed in at least part of the bearing seating ducts each having a maximum crosssection of 1,000 which are open towards the ball and through which the writing medium may flow froma central feed duct connected to the reservoir to the lateral bearing seating. 1

It is now the object of the present invention to devise a method for producing such a writing point which method can be readily performed in practice.

According to the present invention there is provided a method of making a ball point pen or refill therefor, the pen or making a ball point refill having a reservoir for a pasty writing medium and a ball housing connected to one end of the reservoir and providing a support wall and a bearing seating for the ball, the reservoir having at or near its other end an aperture and having an internal cross-section of such dimension that when the ball point pen is held with its writing point upwards, the writing medium does not flow out through the aperture, there being formed in at least part of the bearing seating ducts which are open towards the ball and through which writing medium may flow from a central feed duct connected to the reservoir and the bearing seating, the method including the step of inserting the ball into a ball housing in which the ducts have a cross-sectional area which is greater than 1,000 f with a force suffcient to cause a narrowing of at least a portion of each of the ducts so that the cross-sectional area of said portion does not exceed 1,000

In the present method when the ball is inserted by forcible depression, inmanner known per se, into the bearing seating of the writing point the compression is chosen to be of such magnitude that the cross--sections of the feed passages are narrowed to less than 2,000 .1. preferably less than 1,000 [L2 in the compression zone. Preferably one proceeds in such manner that the bearing seating is compressed so severely that the two longitudinal sides of the passages touch. Forcible depression of the ball into a predrilled writing point is sufficiently well known so that it need not here be discussed in detail. It should only be said that upon pressing the ball against the surfaces which will eventually form the bearing seating, part-spherical formations develop as a result of the compression of the material, which formation may be regarded as islets left in position between the feed passages. Hitherto, however, the compression of the material of the bearing seating surfaces had never been carried so far that by narrowing of the feed passages their cross-section became a maximum of 2,000 1.1. and that therefrom resulted the efiect that the writing medium was still conveyed to the ball when writing with the ball point pen held with its point upwards or in any event with the tip higher than the read end The degree of compression used in individual cases of performing the method depends on the properties of the material of the point of the writing instrument and of that of the bearing seating surfaces. For example, a far lower compression will naturally suffice for brass than if the writing point were to be of steel. The skilled worker will readily establish the compression to be used in individual cases. It only needs a few experiments with different crushing pressures to be made, and after removal of the ball from the point the passage cross-sections are measured.

When practicing the method only those regions of the feed passages are narrowed to the desired cross-section which lie in the compression zone. Those passage regions, on the other hand, which protrude beyond the compression zone, or

beyond the part-spherical base surfaces formed therein, retain their original dimensions which may be considerably more than 2,000 The advantage of the invention resides therein that passages having a cross-section of considerably more than 2,000 may be initially introduces into the base seating of the ball.

Feed passages having the customary cross-section of over 10,000 1.1. may be thrust in in simple manner in accordance with known methods.

An illustrative embodiment of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal cross-section of the writing point of a ball point pen, the position of the ball being indicated in broken lines so as to more clearly show the construction of the feed passages;

FIG. 2 is a view in the direction of the arrow of FIG. 1; and

FIG. 3 is a perspective view of the writing point without the ball, portions of the wall of the point being broken away for the sake of greater clarity.

The writing point includes a housing generally designated by the reference numeral 1 and may be manufactured by planing a cylindrical blank, e.g. a brass blank. The reservoir of the pen (not shown) is connected to the end of the point 1 remote from the ball. Communication between the reservoir and the space enclosed by seating surfaces 2 and 3 for the ball 4 is established by a central supply passage 5', 5", the section 5' of the passage directly adjoining the base seating having a smaller cross-section than the section 5" adjoining the reservoir. The seating surface 2 is in fact the seating surface of the spherical ball cavity, which cavity forms the spherically shaped lateral seat of the ball when the ball 4 has been crimped in position.

A shoulder 6 is formed in the writing point and forms the transition from the lateral seating surface to the base seating surface for the ball. This latter surface is formed by partspherical regions 3 lying between feed passages 8 formed in the base surface prior to insertion of the ball. The part-spherical configuration of the surfaces 3 results from the compression with which the ball is pressed against the base seating surface in the course of producing the writing point. Such compression brings about a substantial narrowing of the feed passages 8 in the compression zone, at the same time. As can be seen from the drawing, the narrowing of the feed passages has been carried to an extent such that their longitudinal side walls contact one another in the compression zone. The contact in point of fact does not extend over the entire length of the passages, just as the entire length of the feed passages is not embraced by the compression or the narrowing (cf. FIG. 3). 1n the ball point pens currently on the market, made to DIN standards, the length of the feed passages is about 200 ,u with a ball diameter of 1 mm. The narrowed zone of the feed passages extends only a fraction thereof. Thus, in producing the ball point pen, the ball will be force-fitted into a housing in which the feed passages initially have a cross-sectional area greater than 1,000 The force exerted on the ball is suffcient to cause a narrowing of that part of each passage which is in the compression zone so that the cross-sectional area of that part does not exceed 2,000 .1. preferably 1,000 In this way the passages achieve the configuration as shown in the drawing.

When the ball 4 has been crimped in position, an annular accumulation groove 7 for the writing medium results between the lateral seating 2 and the base seating 3, this groove being formed in the shoulder 6.

Suitably, the number of feed passages 8 is increased as compared to that of known writing points. This number may, for example be between 10 and 20.

The writing point obtained is preferably used in ball point pens or refills therefor which have the DIN dimensions and a storage container the cross-section of which amounts to less than 10 mm and wherein the reservoir is filled with a pasty writing medium having a viscosity of not less than 10 poises and preferably not more than 250 poises at 37C.

We claim:

1. A method of making a ball point pen writing element, said element including reservoir means, a pasty writing medium in said reservoir means, a ball, a ball housing means, said ball housing means being connected to one end of said reservoir means and defining a ball support wall and bearing seating, said ball being mounted in said ball housing to form a writing tip, means defining an aperture in the region of the other end of the reservoir means, said means defining an aperture being dimensioned such that when the ball point pen is held with its writing tip upwards, the said writing medium does not flow out through the means defining the aperture, central feed duct means, said central feed duct means connecting said reservoir means and said bearing seating, means defining ducts having longitudinal side walls in the seating bearing, said ducts opening towards the ball for supplying said writing medium from said central feed duct means to said ball, the improvement in the method being in that said ball is inserted into a ball housing in which the ducts have a cross-sectional area which is greater than 1,000 with a force sufficient to cause a narrowing of at least a portion of each of said ducts so the cross-sectional area of said portion does not exceed 1 ,000

2. A method of making a ball point pen writing element, said element including reservoir means, a pasty writing medium in said reservoir means, a ball, a ball housing means, said ball housing means being connected to one end of said reservoir means and defining a ball support wall and bearing seat-- ing, said ball being mounted in said ball housing to form a writing tip, means defining an aperture in'the region of the other end of the reservoir means, said means defining an aperture being dimensioned such that when the ball point pen is held with its writing tip upwards, the said writing medium does not flow out through the means defining the aperture, central feed duct means, said central feed duct means connecting said reservoir means and said bearing seating, means defining ducts having longitudinal side walls in the seating bearing, said ducts opening towards the ball for supplying said writing medium from said central feed duct means to said ball, the improvement in the method being in that said ball is inserted into a ball housing in which the ducts have a cross-sectional area which is greater than 2,000 with a force sufficient to cause a narrowing of at least a portion of each of said ducts so that the cross-sectional area of said portions does not exceed 2,000

3. A method according to claim 2, in which said force exerted on said ball is sufficient to cause said longitudinal side walls ofsaid portion ofeach said duct to contact one another. 

1. A method of making a ball point pen writing element, said element including reservoir means, a pasty writing medium in said reservoir means, a ball, a ball housing means, said ball housing means being connected to one end of said reservoir means and defining a ball support wall and bearing seating, said ball being mounted in said ball housing to form a writing tip, means defining an aperture in the region of the other end of the reservoir means, said means defining an aperture being dimensioned such that when the ball point pen is held with its writing tip upwards, the said writing medium does not flow out through the means defining the aperture, central feed duct means, said central feed duct means connecting said reservoir means and said bearing seating, means defining ducts having longitudinal side walls in the seating bearing, said ducts opening towards the ball for supplying said writing medium from said central feed duct means to said ball, the improvement in the method being in that said ball is inserted into a ball housing in which the ducts have a cross-sectional area which is greater than 1,000 Mu 2 with a force sufficient to cause a narrowing of at least a portion of each of said ducts so the cross-sectional area of said portion does not exceed 1,000 Mu
 2. 2. A method of making a ball point pen writing element, said element including reservoir means, a pasty writing medium in said reservoir means, a ball, a ball housing means, said ball housing means being connected to one end of said reservoir means and defining a ball support wall and bearing seating, said ball being mounted in said ball housing to form a writing tip, means defining an aperture in the region of the other end of the reservoir means, said means defining an aperture being dimensioned such that when the ball point pen is held with its writing tip upwards, the said writing medium does not flow out through the means defining the aperture, central feed duct means, said central feed duct means connecting said reservoir means and said bearing seating, means defining ducts having longitudinal side walls in the seating bearing, said ducts opening towards the ball for supplying said writing medium from said central feed duct means to said ball, the improvement in the method being in that said ball is inserted into a ball housing in which the ducts have a cross-sectional area which is greater than 2,000 Mu 2 with a force sufficient to cause a narrowing of at least a portion of each of said ducts so tHat the cross-sectional area of said portions does not exceed 2,000 Mu
 2. 3. A method according to claim 2, in which said force exerted on said ball is sufficient to cause said longitudinal side walls of said portion of each said duct to contact one another. 